title: Self-regulating enzyme-nanotube ensemble films and their application as flexible electrodes for biofuel cells.
abstract: Nanostructured carbons have been widely used for fabricating enzyme-modified electrodes due to their large specific surface area. However, because they are random aggregates of particular or tubular nanocarbons, the postmodification of enzymes to their intrananospace is generally hard to control. Here, we describe a free-standing film of carbon nanotube forest (CNTF) that can form a hybrid ensemble with enzymes through liquid-induced shrinkage. This provides in situ regulation of its intrananospace (inter-CNT pitch) to the size of enzymes and eventually serves as a highly active electrode. The CNTF ensemble with fructose dehydrogenase (FDH) showed the oxidation current density of 16 mA cm(-2) in stirred 200 mM fructose solution. The power density of a biofuel cell using the FDH-CNTF anode and the Laccase-CNTF cathode reached 1.8 mW cm(-2) (at 0.45 V) in the stirred oxygenic fructose solution, more than 80% of which could be maintained after continuous operation for 24 h. Application of the free-standing, flexible character of the enzyme-CNTF ensemble electrodes is demonstrated via their use in the patch or wound form.
authors.affiliation: Department of Bioengineering and Robotics, Tohoku University, 6-6-1 Aramaki Aoba, Sendai 980-8579, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Miyake
authors.forename: Syuhei
authors.initials: S
authors.lastname: Yoshino
authors.forename: Takeo
authors.initials: T
authors.lastname: Yamada
authors.forename: Kenji
authors.initials: K
authors.lastname: Hata
authors.forename: Matsuhiko
authors.initials: M
authors.lastname: Nishizawa
mesh_terms: D056804:Biofuels; D002237:Carbohydrate Dehydrogenases / Q000737:chemistry / Q000378:metabolism*; D004566:Electrodes; D005632:Fructose / Q000737:chemistry; D020576:Gluconobacter / Q000201:enzymology; D008567:Membranes, Artificial; D008958:Models, Molecular; D037742:Nanotubes, Carbon / Q000737:chemistry*
chemical_list: D056804:Biofuels; D008567:Membranes, Artificial; D037742:Nanotubes, Carbon; D005632:Fructose; D002237:Carbohydrate Dehydrogenases; C028761:D-fructose 5-dehydrogenase